ZHCSH29B April   2017  – December 2018 LP87524B-Q1 , LP87524J-Q1 , LP87524P-Q1

PRODUCTION DATA.  

  1. 1 特性
  2. 2 应用
    1.     简化原理图
  3. 3 说明
    1.     效率与输出电流间的关系
  4. 4 修订历史记录
    1.     Device Images
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 I2C Serial Bus Timing Requirements
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Descriptions
      1. 7.3.1 DC-DC Converters
        1. 7.3.1.1 Overview
        2. 7.3.1.2 Transition Between PWM and PFM Modes
        3. 7.3.1.3 Buck Converter Load-Current Measurement
        4. 7.3.1.4 Spread-Spectrum Mode
      2. 7.3.2 Sync Clock Functionality
      3. 7.3.3 Power-Up
      4. 7.3.4 Regulator Control
        1. 7.3.4.1 Enabling and Disabling Regulators
        2. 7.3.4.2 Changing Output Voltage
      5. 7.3.5 Enable and Disable Sequences
      6. 7.3.6 Device Reset Scenarios
      7. 7.3.7 Diagnosis and Protection Features
        1. 7.3.7.1 Power-Good Information (PGOOD pin)
        2. 7.3.7.2 Warnings for Diagnosis (Interrupt)
          1. 7.3.7.2.1 Output Power Limit
          2. 7.3.7.2.2 Thermal Warning
        3. 7.3.7.3 Protection (Regulator Disable)
          1. 7.3.7.3.1 Short-Circuit and Overload Protection
          2. 7.3.7.3.2 Overvoltage Protection
          3. 7.3.7.3.3 Thermal Shutdown
        4. 7.3.7.4 Fault (Power Down)
          1. 7.3.7.4.1 Undervoltage Lockout
      8. 7.3.8 GPIO Signal Operation
      9. 7.3.9 Digital Signal Filtering
    4. 7.4 Device Functional Modes
      1. 7.4.1 Modes of Operation
    5. 7.5 Programming
      1. 7.5.1 I2C-Compatible Interface
        1. 7.5.1.1 Data Validity
        2. 7.5.1.2 Start and Stop Conditions
        3. 7.5.1.3 Transferring Data
        4. 7.5.1.4 I2C-Compatible Chip Address
        5. 7.5.1.5 Auto-Increment Feature
    6. 7.6 Register Maps
      1. 7.6.1 Register Descriptions
        1. 7.6.1.1  OTP_REV
        2. 7.6.1.2  BUCK0_CTRL1
        3. 7.6.1.3  BUCK1_CTRL1
        4. 7.6.1.4  BUCK2_CTRL1
        5. 7.6.1.5  BUCK3_CTRL1
        6. 7.6.1.6  BUCK0_VOUT
        7. 7.6.1.7  BUCK0_FLOOR_VOUT
        8. 7.6.1.8  BUCK1_VOUT
        9. 7.6.1.9  BUCK1_FLOOR_VOUT
        10. 7.6.1.10 BUCK2_VOUT
        11. 7.6.1.11 BUCK2_FLOOR_VOUT
        12. 7.6.1.12 BUCK3_VOUT
        13. 7.6.1.13 BUCK3_FLOOR_VOUT
        14. 7.6.1.14 BUCK0_DELAY
        15. 7.6.1.15 BUCK1_DELAY
        16. 7.6.1.16 BUCK2_DELAY
        17. 7.6.1.17 BUCK3_DELAY
        18. 7.6.1.18 GPIO2_DELAY
        19. 7.6.1.19 GPIO3_DELAY
        20. 7.6.1.20 RESET
        21. 7.6.1.21 CONFIG
        22. 7.6.1.22 INT_TOP1
        23. 7.6.1.23 INT_TOP2
        24. 7.6.1.24 INT_BUCK_0_1
        25. 7.6.1.25 INT_BUCK_2_3
        26. 7.6.1.26 TOP_STAT
        27. 7.6.1.27 BUCK_0_1_STAT
        28. 7.6.1.28 BUCK_2_3_STAT
        29. 7.6.1.29 TOP_MASK1
        30. 7.6.1.30 TOP_MASK2
        31. 7.6.1.31 BUCK_0_1_MASK
        32. 7.6.1.32 BUCK_2_3_MASK
        33. 7.6.1.33 SEL_I_LOAD
        34. 7.6.1.34 I_LOAD_2
        35. 7.6.1.35 I_LOAD_1
        36. 7.6.1.36 PGOOD_CTRL1
        37. 7.6.1.37 PGOOD_CTRL2
        38. 7.6.1.38 PGOOD_FLT
        39. 7.6.1.39 PLL_CTRL
        40. 7.6.1.40 PIN_FUNCTION
        41. 7.6.1.41 GPIO_CONFIG
        42. 7.6.1.42 GPIO_IN
        43. 7.6.1.43 GPIO_OUT
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
        1. 8.2.1.1 Inductor Selection
        2. 8.2.1.2 Input Capacitor Selection
        3. 8.2.1.3 Output Capacitor Selection
        4. 8.2.1.4 Snubber Components
        5. 8.2.1.5 Supply Filtering Components
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11器件和文档支持
    1. 11.1 器件支持
      1. 11.1.1 第三方产品免责声明
    2. 11.2 接收文档更新通知
    3. 11.3 社区资源
    4. 11.4 商标
    5. 11.5 静电放电警告
    6. 11.6 术语表
  12. 12机械、封装和可订购信息

封装选项

请参考 PDF 数据表获取器件具体的封装图。

机械数据 (封装 | 引脚)
  • RNF|26
散热焊盘机械数据 (封装 | 引脚)
订购信息

10.1 Layout Guidelines

The high frequency and large switching currents of the LP87524B/J/P-Q1 make the choice of layout important. Good power supply results only occur when care is given to proper design and layout. Layout affects noise pickup and generation and can cause a good design to perform with less-than-expected results. With a range of output currents from milliamps to 10 A, good power supply layout is much more difficult than most general PCB design. Use the following steps as a reference to ensure the device is stable and maintains proper voltage and current regulation across its intended operating voltage and current range.

  1. Place CIN as close as possible to the VIN_Bx pin and the PGND_Bxx pin. Route the VIN trace wide and thick to avoid IR drops. The trace between the positive node of the input capacitor and the VIN_Bx pin(s) of LP87524B/J/P-Q1, as well as the trace between the negative node of the input capacitor and power PGND_Bxx pin(s), must be kept as short as possible. The input capacitance provides a low-impedance voltage source for the switching converter. The inductance of the connection is the most important parameter of a local decoupling capacitor — parasitic inductance on these traces must be kept as small as possible for proper device operation. The parasitic inductance can be reduced by using a ground plane as close as possible to top layer by using thin dielectric layer between top layer and ground plane.
  2. The output filter, consisting of COUT and L, converts the switching signal at SW_Bx to the noiseless output voltage. It must be placed as close as possible to the device keeping the switch node small, for best EMI behavior. Route the traces between the LP87524B/J/P-Q1 output capacitors and the load direct and wide to avoid losses due to the IR drop.
  3. Input for analog blocks (VANA and AGND) must be isolated from noisy signals. Connect VANA directly to a quiet system voltage node and AGND to a quiet ground point where no IR drop occurs. Place the decoupling capacitor as close as possible to the VANA pin.
  4. If the processor load supports remote voltage sensing, connect the feedback pins FB_Bx of the LP87524B/J/P-Q1 device to the respective sense pins on the processor. The sense lines are susceptible to noise. They must be kept away from noisy signals such as PGND_Bxx, VIN_Bx, and SW_Bx, as well as high bandwidth signals such as the I2C. Avoid both capacitive and inductive coupling by keeping the sense lines short, direct, and close to each other. Run the lines in a quiet layer. Isolate them from noisy signals by a voltage or ground plane if possible. If series resistors are used for load current measurement, place them after connection of the voltage feedback.
  5. PGND_Bxx, VIN_Bx and SW_Bx must be routed on thick layers. They must not surround inner signal layers, which are not able to withstand interference from noisy PGND_Bxx, VIN_Bx and SW_Bx.
  6. If the input voltage is above 4 V, place snubber components (capacitor and resistor) between SW_Bx and ground on all four phases. The components can be also placed to the other side of the board if there are area limitations and the routing traces can be kept short.

Due to the small package of this converter and the overall small solution size, the thermal performance of the PCB layout is important. Many system-dependent parameters such as thermal coupling, airflow, added heat sinks and convection surfaces, and the presence of other heat-generating components affect the power dissipation limits of a given component. Proper PCB layout, focusing on thermal performance, results in lower die temperatures. Wide and thick power traces come with the ability to sink dissipated heat. This can be improved further on multi-layer PCB designs with vias to different planes. This results in reduced junction-to-ambient (RθJA) and junction-to-board (RθJB) thermal resistances and thereby reduces the device junction temperature, TJ. TI strongly recommends to perform of a careful system-level 2D or full 3D dynamic thermal analysis at the beginning product design process, by using a thermal modeling analysis software.